This invention relates to the conversion of energy from naturally occurring sources of mechanical energy, such as the mechanical energy present in ocean surface waves, to electrical energy and, in particular, to the efficient production and transfer of that energy.
Various wave energy converter (WEC) systems are known. For example, reference is made to U.S. patent application Ser. No. 09/379,421 filed Aug. 21, 1999, titled xe2x80x9cWave Energy Converter Utilizing Pressure Differencesxe2x80x9d, assigned to the assignee of the present application and the teachings of which are incorporated herein by reference.
Numerous problems exist in the design of a mechanical system for harnessing the energy contained in ocean waves. Particularly, a problem exists in harnessing this energy efficiently. In addition, there is a further problem of converting the mechanical energy into electrical energy in an efficient manner. A significant difficulty in increasing the efficiency of converting the ocean wave energy into electric energy is due to the fact that the waves vary continuously in amplitude, frequency and phase as function of time.
Applicants"" invention resides, in part, in the recognition that certain parameters and components need to be controlled to optimize the power transfer. Applicants"" invention also resides in the recognition that a power generating mechanical system may be characterized as an effective capacitive (or inductive) element and that an inductive (or capacitive) element may be added to the system to resonate with the effective capacitance (inductance) of the mechanical system to increase the efficiency of the power transfer. Accordingly, systems embodying the invention include inductive (or capacitive) elements tending to cause resonance with the effective capacitance (inductance) of the power generating mechanical system in order to increase the efficiency of the system.
Applicants"" invention also resides in the recognition that the load coupled to the system has an optimum value and in setting the load to such a value to increase the power transfer and the efficiency of the system.
Applicants"" invention also resides in the recognition that the effective capacitance (inductance) of a mechanical energy converter system varies as a function of the frequency of the ocean waves. Accordingly, systems embodying the invention may include a controller responsive to the frequency of the ocean waves for varying the load and/or the value of the inductive (capacitive) element coupled to the system to resonate with the mechanical converter. The controller may also be used to vary the load to ensure that the value of the load applied to the output of an electric generator may be a continuously varying value which ensures the optimum transfer of power into the load.